The present application relates to an optical device, a method of manufacturing the optical device, and a method of manufacturing a master that is used in the optical device, and more particularly, to an optical device having a surface on which a plurality of structural bodies formed by convex portions or concave portions are arranged with a fine pitch that is equal to or smaller than the wavelength of visible light.
Generally, in some optical devices using a transparent substrate that is formed from glass, plastic, or the like, surface processing is performed so as to suppress the surface reflection of light. As surface processing of such a type, there is processing in which fine and dense concavo-convexes (moth eyes) are formed on the surface of the optical device (for example, see “Optical and Electro-Optical Engineering Contact” Vol. 43, No. 11 (2005), p 630-637).
Generally, in a case where periodical concave-convex shapes are disposed on the surface of the optical device, when light is transmitted through the concave-convex shapes, diffraction occurs. Accordingly, a direct advancing component of transmitted light decreases in a large amount. However, in a case where the pitch of the concave-convex shapes is shorter than the wavelength of the transmitted light, diffraction does not occur. Thus, for example, when the concave-convex shape is formed as a rectangular shape as described later, an effective antireflection effect can be acquired for the light of a single wavelength corresponding to the pitch, the depth, or the like.
As a moth-eye structure produced by using electron beam exposure, a moth-eye structure (pitch: about 300 nm; depth: about 400 nm) having a fine tent-like shape is disclosed (for example, see NTT Advanced Technology Corporation “Molding Die Master for Antireflection Bodies (Moth Eye) That Do Not Have Dependency on the Wavelength” online, Searched on Feb. 27, 2008, Internet Website http://keytech.ntt-at.co.jp/nano/prd—0033.html). According to such a moth-eye structure, the antireflection characteristic of high performance having the reflectivity that is equal to or lower than 1% can be acquired.